Method of preparing fertilizer and agricultural stock feed from manure



July 18, 1967 G. ROBUN 3,331,676

M. G. METHOD OF PREPARING FERTILIZER AND AGRICULTURAL STOCK FEED FROMMANURE Filed March 2, 1964 3 Sheets-Sheet 1 y 1957 M. G. G. ROBLiN3,331,676

METHOD OF PREPARING FERTILIZER AND AGRICULTURAL STOCK FEED FROM MANURE VFiled March 2, 1964 3 Sheets-Sheet 2 July 18, 1967 ROBLIN 3,L331,$75

M. G. METHOD OF PREPARING FERTILIZER AND AGRICULTURA STOCK FEED FROMMANURE Filed March 2, 1964 3 Sheets-$heet 3 United States Patent Ofi3,331,676 Patented July 18, 1967 ice 3 331,676 METHOD OF PREPARINGFERTILIZER AND AGRICULTURAL STOCK FEED FROM MA- NURE Mervyn Gwilym GlynRoblin, Reading, England, assignor to Hydraulic Developments Limited,Reading, England, a British company Filed Mar. 2, 1964, Ser. No. 348,666Claims priority, application Great Britain, Mar. 4, 1963, 8,557/63; Oct.30, 1963, 42,800/ 63 4 Claims. (Cl. 71-21) This invention relates tofertilizers, and material suitable for use, after re-fortification, asagricultural stock feed, and is concerned more particularly with theirproduction from poultry excrement and similar excrement in liquid and/orsolid form, from other livestock such as cows, pigs, sheep and horses,such excrement being referred to generally as farm eflluent.

Due to the present-day practice of keeping livestock in large numbers ina relatively small space, large quantities of efl luent are produced. Atpresent, the disposal of this presents serious problems, and adequateprecautions must also be taken to prevent the spread of disease from theefliuent. Furthermore, although the efiiuent contains a relatively highproportion of nitrogen, phosphate and potash, and would therefore bevaluable as a fertilizer or for use with re-fortification asagricultural stock feed, it cannot be employed for these purposes sinceits physical characteristics and the fact that it is not sterilizedrender its transport and application impracticable.

It is an object of the present invention to overcome or alleviate theabove difliculties by producing from farm effiuent a useful andmanageable fertilizer or material suitable for use with re-fortificationas agricultural stock feed.

The present invention consists in a method of producing from excrement afertilizer, or material suitable for use, after re-fortification, asagricultural stock feed, which includes drying the excrement by heatingunder controlled conditions until it is in the form of granulatedmaterial containing less than 15%, and preferably less than 10%,moisture by weight, whilst simultaneously I stirring and cutting, orotherwise mechanically working, the excrement to keep it in an openfriable condition to prevent it binding or burning.

In the accompanying drawings:

FIGURE 1 is a diagrammatic plan view of one form of apparatus forcarrying out the present invention,

FIGURE 2 is a diagrammatic longitudinal section taken on line 2-2 ofFIGURE 1,

FIGURE 3 is a diagrammatic cross-section taken on line 33 of FIGURE 1,

FIGURE 4 is a diagrammatic cross-section taken on line 44 of FIGURE 1,and

FIGURE 5 is a diagrammatic general view of a detail of the apparatus ofFIGURE 1.

In carrying the invention into efiect according to one convenient modeby way of example, the accompanying drawings show apparatus forproducing a fertilizer from poultry excrement.

The apparatus includes a pair of spaced parallel inner walls 1, composedof concrete, each having an outer concrete wall 2 spaced therefrom andparallel thereto, all the walls 1 and 2 extending in a longitudinaldirection and resting upon a concrete base member 3.

A concrete cover 4 extends between the tops of the two inner walls 1,and the space thus defined between the inner walls 1 and the cover 4 issub-divided into a lower chamber 5, an intermediate chamber 6 and anupper chamber 7 by means of a concrete lower dividing member 8 and aconcrete upper dividing member 9 disposed horizontally and resting uponthe steps 10 and 11, respectively, formed in the inner surfaces of eachinner wall 1.

The adjacent tops of each inner wall 1 and its adjacent outer wall 2 arejoined by a member 12, and their ends are also joined so as to providesealed heat insulating cavities 13 on each side of the chambers 5, 6 and7.

Warm air from the room in which the apparatus is situated is drawn intoone end of the lower chamber 5 through an inlet 14 and then along theentire length of the lower chamber 5 by means of a fan 15 mounted in aconduit 16 connected to the other end of the lower chamher 5. Aregulator 17 is provided so that further air may be drawn into conduit16 from the room through a further inlet 18 if so desired.

Under the influence of the fan 15, the air passes through conduit 16over a burner or heater 19 and thence through a hood 20 into one end ofthe intermediate chamber 6 and onto a curved deflector 21 which directsthe stream in the direction of the intermediate chamber 6.

The air stream then passes back in the reverse direction along theentire length of the intermediate chamber 6 until it reaches the far endwhere it is deflected by a further deflector 22 to pass in the firstdirection through the upper chamber 7 until it finall passes out throughoutlet 23 situated outside the room in which the apparatus is located.

It will be appreciated that with this arrangement, the air stream in thelower chamber 5 is pre-heated by the heat from the other two chambers 6and 7, and the loss of heat downwardly from these chambers is reduced.The upper chamber 7 is similarly pre-heated by the intermediate chamber6. In an alternative arrangement, not

shown, the lower chamber 5 may be arranged to constitute a sealed heatinsulating cavity, in which case warm air is drawn into conduit 16directly from the room.

The further deflector 22 is moveable to a lower position, shown inphantom, in which air having travelled through the intermediate chamber6 is recirculated back through the lower chamber 5. Under theseconditions, there is no forced air through the upper chamber 7, butheating of this chamber from underneath is maintained as long as theburner or heater 19 and the fan 15 are kept in operation.

The upper dividing member 9 is arranged to provide a support surface fora layer of excrement undergoing treatment in the upper chamber 7. a

The cover 4 is provided with a central longitudinal slit 24 throughwhich extends a delivery chute 25 of a travelling hopper 26 mounted onwheels for longitudinal movement upon rails 27 resting upon members 12.

In order to prevent the escape of gas from the upper chamber 7, the slit24 is provided with two co-operating flaps 28 which normally engage eachother to seal the slit 24, but which permit the chute 25 to pass throughthe slit into the upper chamber 7 and also permit it to movelongitudinally in the slit whilst maintaining the seal in front of, andbehind, the chute 25.

A travelling agitating device 29 is also mounted on wheels forlongitudinal movement upon rails 27. The device 29 carries an electricalmotor and brake 30 for driving its wheels 31 through a gear train 32 andan axle 33 so that the device 29 may be driven along the rails 27 asrequired. When required, the device 29 may be coupled to the hopper 26,by means of a link 49 on the hopper 26, for traction purposes.

The device 2? also carries a pair of arms 34 which extend downwardlythrough the slit 24 into the upper chamber 7 where they are secured to aframework 35. This framework is shown more clearly in' FIGURE 5 andconsists of a rectangular frame 36 having two longitudinal stiifeningangle members 37.

3 Secured to frame 36 and 37 are two fixed combs 38 and a number ofbearings 39 carry three moveable combs 40 mounted for movement in thebearings 19 transversely of the apparatus.

Each comb 38 or40 consists of a metal arm to which are secured a numberof spaced parallel fingers 41 extending downwardly with their endscloselyspaced from the surface of the upper dividing member 9. Eachfinger 41 is resiliently mounted by means of a portion 42 wound inspring configuration adjacent to the arm to which it is secured. Eachcomb 38 or 40 is provided with a row of eighteen fingers equally spaced3 /2" apart. Each finger is4" long and in diameter.

The three moveable combs 44) are secured to a common arm 43 connected bymeans of flanges 44 to an operating arm 45 which extends upwardlybetween the arms 34 through the slit 24. The upper end of the operatingarm is connected through a reciprocating link 46 to a four-speed gearbox47 and a variable speed electrical motor 48 both mounted upon thestructure of the agitating device 29. In this way, the moveable combs 40may be reciprocated transversely at any desired speed.

'To load the apparatus the hopper 26 is first pushed with the aid of thedevice 29 to the right hand side of the apparatus, as seen in FIGURE 2,where it receives a quantity of excrement from a bulk supply (notshown). The hopper 26 is then drawn from one end of the apparatus to theother, distributing the excrement into the upper chamber 7 through chute25 as it goes. The hopper 26 and device 29 are then returned to theright hand side of the apparatus, and during this movement, a blade 50on the device 29 is lowered to a fixed height to level out the depositedexcrement to a uniform layer of desired thickness.

Using an effective surface area of the upper dividing member 9 ofseventy feet by four feet four inches, between one ton and twenty-fivehundredweight of excrement may be spread out into a layer approximatelytwo inches thick.

The hopper 26 is then uncoupled from the device 29,

and the device 29 is used to agitate the excrement, travelling backwardsand forwards over it, during heating, at

various times to be described more fully hereinafter.

After the treatment has been completed, the device 29 is driven to therighthand side of the apparatus as shown in FIGURE 2, the blade 50 islowered until it is almost touching the surface of the upper dividingmember 9, and the device 29 is driven to the other end of theapparatusso that the blade 50 functions as a scoop or shovel to deliver the finalproduct into a receptacle 51.

In operation, the excrement, loaded into the upper chamber with amoisture content of probably 70%, is

. subjected to the following heat treatment:

(1)/The temperature of the excrement is raised as quickly as possible to212 F. and is maintained at this temperature for one hour, with an airspeed of 25 m.p.h.

During this time, gases with an unpleasant odour are given off probablycontaining a proportion of methane or like gas. No agitation is usedduring this stage. (2) For the next half hour, the temperature isreduced 7 to 190 F., the air speed is maintained at 25 m.p.h., and

agitation is carried out at the rate of a complete traversal of theapparatus from one end to the other, and back again, in a period ofthree minutes, this being repeated atan interval of every seven minutes.During traversal 'the combs are reciprocated at the rate of ten strokesper second. During this stage practically no detectable gas is given offby the excrement. 3

(3) For the nexthalf hour, the temperature is again raised to 212 F.,the air speed is reduced to m.p.h.,

and agitation is carried out at the rate of a complete traversal in aperiod of three minutes, this being repeated at an interval ofapproximately every fifteen minutes. During this stage ammonia .is givenoff, and the agitation is carried out sufiiciently vigorouslyandsufiiciently often to prevent its burning or binding to a hardconcrete-like mass, but yet permitting the formation of a crust orsurface casing of phosphate to retain organic nitrogen in the excrement.

(4) For a final period of half an hour, the temperature is reduced tobetween 140 F. and 150 F., the flow of air is cut off, and the agitationis discontinued except for the last few minutes of this stage when thefinal product, having had its moisture content reduced to less than 15and preferably between 10% and 8%, is mildly agitated. The product isthen in the form of a granular material.

The most valuable component ofthe final product are organic nitrogen,nitrogen compounds, which are very unstable and easily lost. Theexcrement is spread relatively thinly, say in a layer between 1" and 3"thick over a heated base and heatedby hot dry air in an enclosed spaceso that the lower and upper surfaces of the excrement are dried rapidlyto form a crust or phosphate casing, enclosing the wetter excrement. Inorder to prevent the crust or casing burning or binding to a hardconcretelike mass it is necessary, at intervals, to stir the excrementrapidly and thoroughly for'its entire thickness in order to mix the thenbroken crust or casing with the wetter centre portion. After this, anewcrust or forms rapidly, but with a drier centre portion than before. Asexplained above,

. this process is repeated at certain intervals to reduce an Ifdesired,'it is through that the initial drying stage' (1) above might beeliminated if suitable measures are taken to dry the excrement,externally of the apparatus,

to the state where stage (2) above can be commenced I as soon as theexcrement is introduced into the apparatus.

The composition of the final product will vary 'considerably with thecomposition of the initial excrement, and with the conditions of thetreatment, but one such product was found to contain 13% P 0 and 7.8% N.

It is believed that under various circumstances there may be obtained upto 22% of P 0 and up to 10% N. Useful lower limits would be 10% P 0 and4% N. The product may be used directly as a fertilizer, or withappropriate re-fortification at an appropriate stage in the process, asagricultural stock feed.

Since the heated air leaving the outlet of the upper compartment willcontain a vapour having a' high nitrogen content, suitable means areprovided for condensing and/ or dissolving this in water to provide aliquor having valuable properties as a fertilizer. If desired, pureliquid ammonia may be extracted subsequently from this liquor.

Various modifications may be made ,within the scope of the presentinvention.

I claim:

1. A process for the treatment of excrement, which includes the steps ofspreading out said excrement in a relatively thin layer, applyingsufficient heat to said excrement to thereby dry rapidly its surfaces toform a phosphate crust enclosing wetter excrement, during heatingstirring said excrement to break said crust and to thoroughly mix thebroken crust with the said wetter excrement, thereafter intermittentlystirring said excrement whenever a crust has been reformed on theexcrement, continuing said heating and said intermittent stirring untilthe excrement is in the form of a granular material containing less than15% moisture by weight, and recovering the granular material.

2. A process for the production of a fertilizer from excrement, whichincludes the steps of spreading said excrement in a relatively thinlayer, applying sufiicient heat to said excrement to thereby dry rapidlyits. surfaces and promote the formation of a phosphate crust upon saidexcrement,'intermittently stirring said excrement whenever said crusthas been formed to break said crust and mix it with said excrement,discontinuing said heat and said stirring when the excrement is in theform of a granular material containing less than 15% moisture by weight,and recovering said granular material for use as a fertilizer.

3. A process for the production of a fertilizer from excrement, whichincludes the steps of spreading said excrement in a relatively thinlayer having horizontal upper and lower surfaces, applying suflicientheat to said surfaces to cause rapid drying thereof and the formation ofa phosphate crust enclosing wetter excrement, intermittently breakingsaid crust and mixing it with said wetter excrement, discontinuing saidheating and intermittent breaking when the excrement is in the form of adry granular material, and receiving said granular material for use as afertilizer.

4. A process for the production of a fertilizer from excrement, whichincludes the steps of arranging the excrement in a thin layer, applyingsuflicient heat to the excrement to cause rapid drying thereof with theformation of a phosphate crust on the surfaces of the layer, with wetterexcrement between, breaking said crust and mixing it with said Wetterexcrement to prevent the crust turning to a hard concrete-like mass,continuing said heating and said breaking and mixing until the excrementis in the form of a granular material containing less than 15 moistureby Weight, between 4% and 10% N, and between 10% and 22% P 0 andrecovering said granular material for use as a fertilizer.

References Cited UNITED STATES PATENTS 1,320,405 11/1919 Mudd 71-211,420,596 6/ 1922. Webster 7121 1,496,834 6/ 1924 Thompson 71--21 2,906,615 9/ 1959 Dumore 7 l-Zl 3,022,155 2/ 1962 Syers 7164 X S. LEONBASHORE, Acting Primary Examiner.

DONALL H. SYLVESTER, ANTHONY SCLAMMANA,

R. BAJEFSKY, Assistant Examiners.

1. A PROCESS FOR THE TREATMENT OF EXCREMENT, WHICH INCLUDES THE STEPS OFSPREADING OUT SAID EXCREMENT IN A RELATIVELY THIN LAYER, APPLYINGSUFFICIENT HEAT TO SAID EXCREMENT TO THEREBY DRY RAPIDLY ITS SURFACES TOFORM A PHOSPHATE CRUST ENCLOSING WETTER EXCREMENT, DURING HEATINGSTIRRING EXCREMENT TO BREAK SAID CRUST AND TO THOROUGHLY MIX THE BROKENCRUST WITH THE SAID WETTER EXCREMENT, THEREAFTER INTERMITTENTLY STIRRINGSAID EXCREMENT WHENEVER A CRUST HAS BEEN REFORMED ON THE EXCREMENT,CONTINUING SAID HEATING AND SAID INTERMITTENT STIRRING UNTIL THEEXCREMENT IS IN THE FORM OF A GRANULAR MATERIAL CONTAINING LESS THAN 15%MOISTURE BY WEIGHT, AND RECOVERING THE GRANULAR MATERIAL.